¹ Subject to availability for the length of the stay, provided the room was not booked through a prepaid, third-party channel, including priceline.com, expedia.com, booking.com, orbitz.com, elong.com and delta.com. Enhanced rooms are rooms on higher floors, corner rooms, newly renovated rooms and rooms with preferred views. Enhanced rooms do not include suites. Not offered at AloftSM and ElementSM hotels.
² Based on local hotel time. Subject to availability only at resorts and conference center hotels.

Conclusion

There is not harm done by signing up for Corporate Preferred if you occasionally stay at Starwood properties, but not enough to get any status with them. You don’t have to book the rates associated with the company you sign up (no idea to whom this SET even belongs to).